Clock Speed

Clock speed is the number of cycles a CPU performs each second, measured in gigahertz (GHz). A 3.5 GHz processor runs 3.5 billion cycles per second, and in each cycle it can carry out part or all of one or more instructions. A higher clock speed generally means faster processing.

Clock speed alone does not decide performance. The number of cores, the amount of cache and the architecture, which affects how many instructions run per cycle, matter just as much. Modern CPUs also change their speed automatically, raising it (turbo or boost) under heavy load and lowering it to save power.